Dialkylpalladium(II) Complexes. Syntheses, Characterizations, and Reactions with CO, I2, and CH3I

The reaction of bis(acetylacetonato)palladium(II), [Pd(acac)2] with AlR2(OEt) in the presence of tertiary phosphine, L, in diethyl ether yields a series of dialkylpalladium(II) complexes, [PdR2L2], where R=Me, Et, and Prn; L=PEt3, PPh2Me, and 1/2Ph2PCH2CH2PPh2 (dpe). These complexes were characterized by means of elemental analysis, IR and 1H-NMR spectra and of some decomposition reaction such as thermolysis and acidolysis. The trans- and cis-configurations of [PdMe2L2] (L=PEt3 and PPh2Me, respectively) in solution were established on the basis of the 1H-NMR spectra. The examination of 1H-NMR spectra in the presence of tertiary phosphine suggests the ligand exchange processes promoted by the added phosphine. [PdR2L2] (L=PEt3 and PPh2Me) reacted with CO in toluene to yield the quantitative amounts of the corresponding dialkyl ketones. The reactions of the complexes [PdR2L2] with iodine afforded [PdI2L2] and RI, and of [PdR2(dpe)] with MeI gave CH3H, CH3CH3, R(–H), RH, R·CH3, R·R, and RI together with [PdI2L2], suggesting the presence of a quadrivalent, six-coordinate intermediate palladium species.